Is everything we thought we knew about American dietary habits wrong? A new study published in PLoS One found that through its 39-year history, the National Health and Nutrition Examination Survey (NHANES) data for more than half the respondents was "not physiologically plausible."

NHANES, which started in the 1960s, surveys a sample of 5,000 people a year, combining interviews with physical examinations. The study examines health and nutrition trends to focus on emerging needs, but this review finds that much of the numbers are inaccurate.

The study, led by Edward Archer, found that plenty of the numbers reported in the survey were "physiologically implausible." Researchers found that oftentimes, subjects misreported the amount of food they ate, especially if they fell into the obese category.

"Given the indirect, pseudo-quantitative nature of the method... nutrition surveys frequently report a range of energy intakes that are not representative of the respondents’ habitual intakes, and estimates of [energy intake] that are physiologically implausible (i.e., incompatible with survival) have been demonstrated to be widespread," the study concludes.

Across the board, the researchers found that men underreported how much they ate by 12 to 14 percent, while women underreported their caloric intake by 16 to 20 percent. In general, the data of 67.3 percent of women and 58.7 percent of men collected by the NHANES was deemed invalid by Archer and his team.

"It is time to stop spending tens of millions of health research dollars collecting invalid data and find more accurate measures," Archer said to PopSci. Read the full report at PLoS One.